1. Field of the Invention
The present invention relates to the management and conservation of landscape irrigation water and more specifically, to methods and apparatus for automatically adjusting irrigation based upon changing environmental conditions, geographic locations and/or government watering restriction regulations.
2. Description of the Prior Art
Many regions of the United States lack sufficient water resources to satisfy all of their competing agricultural, urban, commercial and environmental needs. Landscape water conservation has therefore become an important issue in the landscape irrigation industry. One reason that landscape water is over-utilized is that most consumers typically adjust their irrigation schedule an average of three times per year, rather than on a daily or weekly basis, regardless of changes in environmental conditions. The relatively high cost of labor in many municipalities prohibits frequent manual adjustments of such irrigation controllers. This generally results in over-irrigation and runoff, particularly during the off-seasons, oftentimes by as much as one to two hundred percent. Certain municipalities or water districts limit landscape irrigation to certain times of the day, certain days of the week, or certain days of the month. However, these require manually entered programming changes several times during the course of the year, resulting in generally limited compliance and efficiency. The Southern Nevada Water Authority (SNWA) recently reported that only 7% of their customers were totally compliant year round. It is therefore desirable to provide methods and apparatus for automatically adjusting landscape irrigation based upon changing environmental conditions, geographic locations and/or government regulations.
There have been three primary approaches used to accomplish the goal of conserving landscape irrigation water: (1) water conservation through restricted watering schedules (such as municipal or governmental watering restrictions); (2) soil moisture sensing methods; and (3) climate-based irrigation systems and methods using “smart” (self-adjusting) irrigation controllers.
Municipal watering restrictions have been used by municipalities for about 30 years to both save water and address the water load demand on pumping and infrastructure water delivery capacities. These restrictions have heretofore been manually entered into irrigation controllers and normally require manual seasonal changes. The present inventor's U.S. Pat. Nos. 7,844,368 and 7,962,244 and published application No. 2011/0093123, which are incorporated herein, discuss methods and apparatus for implementing municipally restricted watering schedules. These restrictions can be provided within an irrigation controller, through devices that are plugged into a controller, through devices that are added onto a controller, or through systems for centrally broadcasting information to remote controllers, add-ons or plug-ins. Additional embodiments for implementing restricted watering schedules are disclosed herein.
Soil moisture sensing devices have been in available for years, but have enjoyed only limited success. Such devices and methods generally call for inserting moisture sensors into the soil to measure the soil moisture content. Conventional soil moisture sensors typically break either the common electrical line to the valves, or break the electrical line for each individual valve. Irrometer provides such soil moisture sensors. Newer soil moisture sensing technologies have more recently been developed, such as by Acclima and Baseline, and claim to be more accurate in measuring plant water needs. Improved soil moisture technology may be promising, but such devices and methods are often problematic due to the location and number of sensors necessary, and the high costs of installing and maintaining the sensors. Nevertheless, newer and more accurate soil moisture sensing devices can provide useful data for use by “smart” (self-adjusting) irrigation controllers with which these newer sensors communicate, and related devices, including embodiments of the present invention.
In terms of climatologically based smart controllers, a number of irrigation controller manufacturers offer smart irrigation controllers that calculate evapotranspiration, or “ET”, which is a representation of the amount of water needed by plants to replace water lost through plant absorption and evaporation, and is expressed in inches or millimeters of water per day. Unfortunately, as described briefly below and in more detail in predecessor U.S. Pat. No. 7,058,478 (which is incorporated herein by this reference), because there are so many different methods of calculating ET, and because so many different variables may be taken into consideration in making ET calculations, any controller or related device that actually performs ET calculations is likely to generate erroneous or unpredictable results, which is not desirable when trying to regulate landscape irrigation.
The United States Food and Agriculture Office (USFAO), in its Irrigation and Drainage Paper No. 24, entitled “Crop Water Requirements,” noted that “a large number of more or less empirical methods have been developed over the last fifty years by numerous scientists and specialists worldwide to estimate ET from different climatic variables.”
There are at least 15 different recognized ET formulas. Each of these formulas provides a different result for the reference ET (ETo). In their paper entitled “Methods to Calculate Evapotranspiration Differences and Choices,” Diego Cattaneo and Luke Upham published a four-year analysis comparing four different recognized ETo formulas—the Penman-Monteith formula, the Schwab formula, the Penman formula, and the Penman program described in the previous patents. The comparison revealed that the results from these four recognized formulas sometimes varied by as much as seventy percent, particularly with the most recognized Pennman-Monteith formula discussed at length in the parent applications. (See the '478 patent col. 2, starting at line 56; and see the '428 and '368 patents, FIG. 8; and see FIG. 8 of the pending published application 2011/0093123). The following U.S. patents, among others, disclose various methods by which an irrigation controller calculates or adjusts an irrigation schedule based upon historical, distal, or local ETo: U.S. Pat. Nos. 4,962,522; 5,208,855; 5,479,339; 5,696,671; and 6,298,285. Unlike embodiments of the present invention, all of these inventions either calculate ETo (“reference” ET) values from weather stations or environmental sensors, or receive current service based ET data from external sources, and use such ET information to adjust and regulate irrigation. Several of these existing inventions also utilize other data, such as a precipitation sensor or a freeze sensor to shut down irrigation, respectively, during rainy times or cold temperatures. None of these prior inventions, however, actually perform an automated water budget calculation. Conversely, embodiments of the present invention do not themselves make any ET determinations or calculations, and do not receive or transmit current ET data; however, embodiments of the present invention may utilize or rely on historical ET data in determining the water budget percentage without making ET calculations within the embodiments. Such external sources may be CIMIS (California Irrigation Management Information System) ET databases, local sensors, cable lines or broadcast stations. Such historical ET data was used to develop FIG. 1 of the parent patents and the pending published application 2011/0093123.
The main objection to using ET based controllers, add-ons and plug-ins is that they either calculate ET or receive ET data in order to determine the irrigation schedule and are far too complex for the average user. A 2009 study sponsored by the California Department of Water Resources (DWR) conducted by AquaCraft revealed that of the 3112 ET based smart irrigation controllers used in the California study, 47% used more water than the previous conventional controllers at the same locations during the previous year. The total resulting overall average landscape water saved was a disappointing 6.3%. As a consequence, many irrigation controller manufacturers such as Toro, Irritrol, Rain Bird, and Hunter have recently gone away from calculated ET based systems and transmitted ET based service fees, particularly for residential applications, in favor of much simpler and less expensive approaches.
In addition to its user unfriendliness, a second shortcoming of the calculated ET method is its dependence upon numerous categories of local, real-time meteorological data and a variety of landscape specific data such as the sprinkler precipitation rate, crop coefficient factors, type of soil, slope, degree of shade, etc. Data used for calculating current ET must be obtained by separate sensors, each one installed in a particular location, requiring an understanding of local environmental conditions and meteorology. Such current data must be received and processed in real-time, and any inaccurate, misinterpreted or misunderstood data would result in inaccurate current ET calculations, leading to potential deviations and inefficient irrigation. Historical ET, however, averaged over time, is less susceptible to such deviations.
Due to the urgency arising from severe national drought and environmental conditions, and the shortcomings of the various present technologies, the irrigation industry is still, as it was in 2003, researching alternative methods for water conservation and prevention of unattended runoff. The Center for Irrigation Technology in Fresno, Calif., along with other educational and research institutions and water conservation agencies, is conducting studies to determine the most effective water conservation method. On the national level, the EPA is in the final stages of implementing a “WaterSense” irrigation efficiency rating program similar to the “EnergyStar” rating system currently in use for equipment energy efficiency. The purpose of such an irrigation efficiency rating program is to promote consumer awareness and compliance as an alternative to mandated water conservation measures which would severely and negatively impact the irrigation industry, landscape aesthetics and the ecology. The main criteria for WaterSense labeling is passing the SWAT test while producing at least a 20% landscape water savings, and the capability to incorporate restricted watering schedules. However, there is no specification or means provided for any form of changes to automate watering restrictions during the course of the year, nor the ability to select from one or more set of watering restrictions, including the incorporation of stages of drought.
It is clear from the foregoing discussion that the landscape irrigation industry, in view of a politically and economically sensitive, and urgent, water crisis, is pursuing highly scientific, mathematical and/or technical approaches for resolving the problems of wasted irrigation water and drought conditions. Unsurprisingly, such approaches have met with limited success in a decade of use. The EPA, United States Department of Energy (DOE), ecologists, environmentalists, municipalities, water agencies, and research institutions are all searching for new methods that provide practical (as opposed to theoretical) irrigation efficiency—methods that overcome the particular shortcomings of the prior art.
Thus, there is an urgent need for irrigation systems that conserve water and energy, and minimize negative impact upon the environment, by automatically adjusting their schedules periodically in response to meteorological and seasonal changes, as well as complying with any governmentally-mandated watering restrictions.
The problem of irrigation mismanagement, and the main hurdle faced by the industry, can be simply summarized as follows: once a system is properly designed and installed, most of the wasted landscape irrigation water and runoff is caused by failing to adjust irrigation based on daily, periodic, or seasonal weather changes. Such inaction is usually caused by the complexity and difficulty of determining the particular adjustment amounts. With that in mind, correspondingly simple intuitive solutions would be highly preferred over the existing highly theoretical and technical, but impractical, state of the art in moisture sensing or ET-based control systems.
It is therefore desirable to provide simple, user-intuitive, and therefore readily acceptable water conservation approaches, particularly for clearly understood automated methods of adjusting and implementing irrigation schedules. It is further desirable to provide methods and apparatus that do not necessarily rely upon ground or air moisture sensing means, weather stations, or performing ET calculations (either directly, or as a basis for deriving watering times). It is further desirable to provide methods and apparatus that minimize the margins and sources of errors by minimizing the number of sensor inputs required by the variables in whatever formula is used. It is further desirable to provide methods and apparatus that utilize minimal local, real-time meteorological data. It is further desirable that such methods and apparatus be cost-efficient, affordable and usable by a large number of people and entities within the different industries. It is further desirable that such methods and apparatus be understandable by the average consumer. It is further desirable that such methods and apparatus be accomplished automatically, without requiring regular manual adjustments by the operator of the irrigation watering time settings or schedules. It is also desirable to provide either as an alternative or in combination automated implementation of governmental watering restrictions along with simple automated water budget or seasonal adjust functionality.